U.S. patent application number 11/624974 was filed with the patent office on 2008-07-24 for ischemia detection using pressure sensor.
This patent application is currently assigned to CARDIAC PACEMAKERS, INC.. Invention is credited to Richard Fogoros, Abhilash Patangay, Krzysztof Z. Siejko, Yi Zhang.
Application Number | 20080177156 11/624974 |
Document ID | / |
Family ID | 39470850 |
Filed Date | 2008-07-24 |
United States Patent
Application |
20080177156 |
Kind Code |
A1 |
Zhang; Yi ; et al. |
July 24, 2008 |
ISCHEMIA DETECTION USING PRESSURE SENSOR
Abstract
This document discusses, among other things, a system and method
for sensing a pulmonary artery pressure ("PAP") signal of a
pulmonary artery ("PA") and computing an indication of a reduction
of blood supply to at least a portion of a heart using information
from the PAP signal. The reduction of blood supply to at least a
portion of the heart can be detected using a PAP signal
characteristic or measurement, using a change in the PAP, using an
interval between multiple PAP signal features, using a mitral valve
performance, or using information from the PAP and information from
a different physiological signal, including a cardiac signal, a
heart sound signal, right ventricular pressure signal, a left
ventricular pressure signal, a blood pressure signal, and an oxygen
saturation signal.
Inventors: |
Zhang; Yi; (Blaine, MN)
; Siejko; Krzysztof Z.; (Maple Grove, MN) ;
Fogoros; Richard; (Pittsburg, PA) ; Patangay;
Abhilash; (Little Canada, MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Assignee: |
CARDIAC PACEMAKERS, INC.
ST. PAUL
MN
|
Family ID: |
39470850 |
Appl. No.: |
11/624974 |
Filed: |
January 19, 2007 |
Current U.S.
Class: |
600/301 ;
600/486 |
Current CPC
Class: |
A61B 5/145 20130101;
A61B 5/0215 20130101; A61B 5/0205 20130101; A61B 5/02028
20130101 |
Class at
Publication: |
600/301 ;
600/486 |
International
Class: |
A61B 5/0205 20060101
A61B005/0205; A61B 5/0215 20060101 A61B005/0215 |
Claims
1. A system comprising: an implantable chronic pulmonary artery
("PA") pressure sensor, configured to chronically sense a pulmonary
artery pressure ("PAP") signal of a PA; and an implantable or
external processor, communicatively coupled to the PA pressure
sensor to receive PAP information, wherein the processor is
configured to use the PAP information to compute an indication of a
reduction of blood supply to at least a portion of a heart.
2. The system of claim 1, wherein the PA pressure sensor is
configured to be fixed to a location within the PA.
3. The system of claim 1, wherein the processor is configured to
compute the indication of a reduction of blood supply using a
change in the PAP.
4. The system of claim 1, wherein the processor is configured to
detect at least one feature of the PAP signal; wherein the
processor includes a time interval detector that is configured to
detect at least one interval between the at least one feature of
the PAP signal occurring at a first time and the at least one
feature of the PAP signal occurring at a second time; and wherein
the processor is configured to compute the indication of a
reduction of blood supply to at least a portion of the heart using
information from the at least one interval between the at least one
feature of the PAP signal occurring at a first time and the at
least one feature of the PAP signal occurring at a second time.
5. The system of claim 1, wherein the processor is configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart using at least one measurement correlative to
at least one of a change in left ventricle ("LV") pressure, a
change in LV diastolic pressure, a change in LV volume, and a rate
of pressure change in the LV ("LV dP/dt").
6. The system of claim 1, wherein the processor is configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart using a detected change in a PA pressure
characteristic, where the PA pressure characteristic includes at
least one of a PA diastolic ("PAD") pressure, a PA systolic ("PAS")
pressure, a mean PAP, and a rate of pressure change in the PA ("PA
dP/dt").
7. The system of claim 1, wherein the processor is configured to
compute the indication of a reduction of blood supply to a
myocardium of a left ventricle.
8. The system of claim 1, wherein the processor is configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart by comparing at least a portion of the PAP
information to a baseline.
9. The system of claim 1, wherein the processor is configured to
use the PAP information to detect an indication of mitral valve
performance, and wherein the processor is configured to compute an
indication of a reduction of blood supply to at least a portion of
the heart using the detected indication of mitral valve
performance.
10. The system of claim 1, including: an auxiliary physiological
sensor, communicatively coupled to the processor, configured to
sense a different physiological signal; and wherein the processor
is configured to compute the indication of a reduction of blood
supply to at least a portion of the heart using the PAP information
and information from the different physiological signal.
11. The system of claim 10, wherein the auxiliary physiological
sensor is configured to sense a different physiological signal
indicative of a reduction of blood supply to at least a portion of
the heart.
12. The system of claim 10, wherein the processor is configured to
detect at least one feature of the different physiological signal
and at least one feature of the PAP signal; wherein the processor
includes a time interval detector that is configured to detect at
least one interval between the at least one different physiological
signal feature and the at least one PAP signal feature; and wherein
the processor is configured to compute the indication of a
reduction of blood supply to at least a portion of the heart using
the at least one interval between the at least one different
physiological signal feature and the at least one PAP signal
feature.
13. The system of claim 10, wherein the auxiliary physiological
sensor includes a cardiac sensor, configured to sense a cardiac
signal as the different physiological signal.
14. The system of claim 10, wherein the auxiliary physiological
sensor includes a heart sound sensor, configured to sense a heart
sound signal as the different physiological signal.
15. The system of claim 10, wherein the auxiliary physiological
sensor includes at least one of a right ventricular pressure
sensor, a left ventricular pressure sensor, a blood pressure
sensor, and an oxygen saturation sensor.
16. The system of claim 10, wherein the processor is configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart using the PAP signal, the different
physiological signal, and at least one weighting factor for the PAP
signal or the different physiological signal.
17. The system of claim 16, wherein the at least one weighting
factor for the PAP signal or the different physiological signal
includes at least one of a signal-to-noise ratio ("SNR") and a
performance metric, wherein the performance metric includes at
least one of a sensitivity, a specificity, a positive prediction
value ("PPV"), and a negative prediction value ("NPV").
18. The system of claim 10, wherein the processor is configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart using a temporal profile, wherein the temporal
profile includes using the PAP information and information from the
different physiological signal in a sequential manner.
19. The system of claim 1, including: an implantable respiration
sensor, configured to sense a respiration signal; an implantable or
external respiration phase detector, coupled to the respiration
sensor, configured to detect at least one phase of the respiration
signal; and wherein the processor is communicatively coupled to the
respiration phase detector to receive respiration information, and
wherein the processor is configured to use the PAP information and
the respiration information to compute the indication of the
reduction of blood supply to at least a portion of the heart,
including at least one of: the processor being configured to form a
composite signal using at least a portion of the PAP signal over at
least a portion of the at least one phase of the respiration
signal; the processor being configured to obtain a gated PAP signal
using information from the respiration phase detector; and the
processor being configured to enable or disable the PA pressure
sensor during at least a portion of at least one phase of the
respiration signal.
20. A system comprising: means for chronically implantably sensing
a pulmonary artery pressure ("PAP") signal of a pulmonary artery
("PA"); and means for using the PAP signal to compute an indication
of a reduction of blood supply to at least a portion of a
heart.
21. A method comprising: chronically implantably sensing a
pulmonary artery pressure ("PAP") signal of a pulmonary artery
("PA"); and using the PAP signal for computing an indication of a
reduction of blood supply to at least a portion of a heart.
22. The method of claim 21, wherein the sensing includes using an
implantable chronic PA pressure sensor configured to be fixed
within the PA.
23. The method of claim 21, wherein the using the PAP signal
includes using a change in the PAP.
24. The method of claim 21, including: detecting at least one
feature of the PAP signal; detecting at least one interval between
the at least one feature of the PAP signal occurring at a first
time and the at least one feature of the PAP signal occurring at a
second time; and wherein computing the indication of a reduction of
blood supply to at least a portion of the heart includes using
information from the at least one interval between the at least one
feature of the PAP signal occurring at a first time and the at
least one feature of the PAP signal occurring at a second time.
25. The method of claim 21, wherein computing the indication of a
reduction of blood supply to at least a portion of the heart
includes using at least one measurement correlative to at least one
of a change in left ventricle ("LV") pressure, a change in LV
diastolic pressure, a change in LV volume, and a rate of pressure
change in the LV ("LV dP/dt").
26. The method of claim 21, wherein computing the indication of a
reduction of blood supply to at least a portion of the heart
includes using a detected change in a PA pressure characteristic,
where the PA pressure characteristic includes at least one of a PA
diastolic ("PAD") pressure, a PA systolic ("PAS") pressure, a mean
PAP, and a rate of pressure change in the PA ("PA dP/dt").
27. The method of claim 21, wherein computing the indication of a
reduction of blood supply to at least a portion of the heart
includes using at least one measurement of the PAP signal to
compute an indication of a reduction of blood supply to a
myocardium of a left ventricle.
28. The method of claim 21, wherein computing the indication of a
reduction of blood supply to at least a portion of the heart
includes comparing at least one measurement of the PAP signal to a
baseline.
29. The method of claim 21, including using the PAP signal for
detecting an indication of mitral valve performance; and wherein
computing the indication of a reduction of blood supple to at least
a portion of the heart includes using the detected indication of
mitral valve performance.
30. The method of claim 21, including: sensing a different
physiological signal; and computing the indication of a reduction
of blood supply to at least a portion of the heart using the PAP
signal and the different physiological signal.
31. The method of claim 30, wherein sensing a different
physiological signal includes sensing a different physiological
signal that is indicative of a reduction of blood supply to at
least a portion of the heart.
32. The method of claim 30, including: detecting at least one
feature of the different physiological signal; detecting at least
one feature of the PAP signal; detecting at least one interval
between the at least one different physiological signal feature and
the at least one PAP signal feature; and wherein computing the
indication of a reduction of blood supply to at least a portion of
the heart includes using the at least one interval between the at
least one different physiological signal feature and the at least
one PAP signal feature.
33. The method of claim 30, wherein sensing a different
physiological signal includes sensing a cardiac signal as the
different physiological signal.
34. The method of claim 30, wherein sensing the different
physiological signal includes sensing a heart sound signal as the
different physiological signal.
35. The method of claim 30, wherein sensing the different
physiological signal includes sensing at least one of a right
ventricular pressure signal, a left ventricular pressure signal, a
blood pressure signal, and an oxygen saturation signal as the
different physiological signal.
36. The method of claim 30, wherein computing the indication of a
reduction of blood supply to at least a portion of the heart
includes using the PAP signal, the different physiological signal,
and at least one weighting factor for the PAP signal or the
different physiological signal.
37. The method of claim 36, wherein using the at least one
weighting factor for the PAP signal or the different physiological
signal includes using at least one of a signal-to-noise ratio
("SNR") and a performance metric, wherein using the performance
metric includes using at least one of a sensitivity, a specificity,
a positive prediction value ("PPV"), and a negative prediction
value ("NPV").
38. The method of claim 30, wherein computing the indication of a
reduction of blood supply to at least a portion of the heart
includes using a temporal profile, wherein using the temporal
profile includes using the PAP signal and the different
physiological signal in a sequential manner.
39. The method of claim 21, including: sensing a respiration
signal; detecting at least a portion of at least one phase of the
respiration signal; and using the PAP signal and respiration signal
information for computing the indication of the reduction of blood
supply to at least a portion of the heart, including at least one
of: forming a composite signal using at least a portion of the PAP
signal over at least a portion of at least one phase of the
respiration signal; obtaining a gated PAP signal using information
from the respiration signal; and enabling or disabling the sensing
the PAP signal using at least a portion of at least one phase of
the respiration signal.
Description
TECHNICAL FIELD
[0001] This patent document pertains generally to cardiac health,
and more particularly, but not by way of limitation, to ischemia
detection using a pressure sensor.
BACKGROUND
[0002] The heart is the center of the circulatory system of the
human body. The left-sided chambers of the heart, including the
left atrium and the left ventricle, draw blood from the lungs and
pump it to the organs of the body to provide the organs with
oxygenated blood. The right-sided chambers of the heart, including
the right atrium and the right ventricle, draw blood from the
organs and pump it into the lungs where the blood gets oxygenated.
The organs of the body require oxygen to survive. Myocardial
ischemia is generally the reduction of blood supply to the heart.
Insufficient blood supply can cause the tissue of the heart to
become hypoxic, or anoxic, and could eventually lead to the death
of the heart tissue. Sudden occlusion of blood supply to the heart
typically results in acute myocardial infarction, or a heart
attack.
Overview
[0003] This overview is intended to provide an overview of the
subject matter of the present patent application. It is not
intended to provide an exclusive or exhaustive explanation of the
invention. The detailed description is included to provide further
information about the subject matter of the present patent
application.
[0004] Generally, left ventricle end diastolic pressure ("LVEDP")
is the pressure in the left ventricle ("LV") at the end of the
filling phase of the heart, and left atrial pressure ("LAP") is the
pressure in the left atrium ("LA") throughout the cardiac cycle.
Typically, LVEDP or LAP can be used to detect a reduction of blood
supply to the heart or an occlusion of blood supply to the heart.
Direct measurement of LVEDP or LAP generally requires direct
placement of a catheter in the LV or the LA. Indirect measurement
of LVEDP generally requires placement of a catheter in the
pulmonary artery ("PA") to measure the pulmonary capillary wedge
pressure ("PCWP"), which is typically correlated to LVEDP. However,
catheter placement is generally not preferred for chronic long-term
monitoring. Thus, the present inventors have recognized, among
other things, a need for detecting a reduction in blood supply to
the heart using a chronic device.
[0005] This document discusses, among other things, a system and
method for sensing a pulmonary artery pressure ("PAP") signal of a
PA and computing an indication of a reduction of blood supply to at
least a portion of a heart using information from the PAP signal.
The reduction of blood supply to at least a portion of the heart
can be detected using a PAP signal characteristic or measurement,
using a change in the PAP, using an interval between multiple PAP
signal features, using a mitral valve performance, or using
information from the PAP and information from a different
physiological signal, including a cardiac signal, a heart sound
signal, right ventricular pressure signal, a left ventricular
pressure signal, a blood pressure signal, and an oxygen saturation
signal.
[0006] In Example 1, a system includes an implantable chronic PA
pressure sensor, configured to chronically sense a PAP signal of a
PA, and an implantable or external processor, communicatively
coupled to the PA pressure sensor to receive PAP information,
wherein the processor is configured to use the PAP information to
compute an indication of a reduction of blood supply to at least a
portion of a heart.
[0007] In Example 2, the PA pressure sensor of Example 1 is
optionally configured to be fixed to a location within the PA.
[0008] In Example 3, the processor of Examples 1-2 is optionally
configured to compute the indication of a reduction of blood supply
using a change in the PAP.
[0009] In Example 4, the processor of Examples 1-3 is optionally
configured to detect at least one feature of the PAP signal,
wherein the processor includes a time interval detector that is
configured to detect at least one interval between the at least one
feature of the PAP signal occurring at a first time and the at
least one feature of the PAP signal occurring at a second time, and
wherein the processor is configured to compute the indication of a
reduction of blood supply to at least a portion of the heart using
information from the at least one interval between the at least one
feature of the PAP signal occurring at a first time and the at
least one feature of the PAP signal occurring at a second time.
[0010] In Example 5, the processor of Examples 1-4 is optionally
configured to compute the indication of a reduction of blood supply
to at least a portion of the heart using at least one measurement
correlative to at least one of a change in LV, a change in LV
diastolic pressure, a change in LV volume, and a rate of pressure
change in the LV ("LV dP/dt").
[0011] In Example 6, the processor of Examples 1-5 is optionally
configured to compute the indication of a reduction of blood supply
to at least a portion of the heart using a detected change in a PA
pressure characteristic, where the PA pressure characteristic
includes at least one of a PA diastolic ("PAD") pressure, a PA
systolic ("PAS") pressure, a mean PAP, and a rate of pressure
change in the PA ("PA dP/dt").
[0012] In Example 7, the processor of Examples 1-6 is optionally
configured to compute the indication of a reduction of blood supply
to a myocardium of a left ventricle.
[0013] In Example 8, the processor of Examples 1-7 is optionally
configured to compute the indication of a reduction of blood supply
to at least a portion of the heart by comparing at least a portion
of the PAP information to a baseline.
[0014] In Example 9, the processor of Examples 1-8 is optionally
configured to use the PAP information to detect an indication of
mitral valve performance, and wherein the processor is configured
to compute an indication of a reduction of blood supply to at least
a portion of the heart using the detected indication of mitral
valve performance.
[0015] In Example 10, the system of Examples 1-9 optionally
includes an auxiliary physiological sensor, communicatively coupled
to the processor, configured to sense a different physiological
signal. The processor is also optionally configured to compute the
indication of a reduction of blood supply to at least a portion of
the heart using the PAP information and information from the
different physiological signal.
[0016] In Example 11, the auxiliary physiological sensor of
Examples 1-10 is optionally configured to sense a different
physiological signal indicative of a reduction of blood supply to
at least a portion of the heart.
[0017] In Example 12, the processor of Examples 1-11 is optionally
configured to detect at least one feature of the different
physiological signal and at least one feature of the PAP signal.
The processor also optionally includes a time interval detector
that is configured to detect at least one interval between the at
least one different physiological signal feature and the at least
one PAP signal feature. The processor is also optionally configured
to compute the indication of a reduction of blood supply to at
least a portion of the heart using the at least one interval
between the at least one different physiological signal feature and
the at least one PAP signal feature.
[0018] In Example 13, the auxiliary physiological sensor of
Examples 1-12 optionally includes a cardiac sensor, configured to
sense a cardiac signal as the different physiological signal.
[0019] In Example 14, the auxiliary physiological sensor of
Examples 1-13 optionally includes a heart sound sensor, configured
to sense a heart sound signal as the different physiological
signal.
[0020] In Example 15, the auxiliary physiological sensor of
Examples 1-14 optionally includes at least one of a right
ventricular pressure sensor, a left ventricular pressure sensor, a
blood pressure sensor, and an oxygen saturation sensor.
[0021] In Example 16, the processor of Examples 1-15 is optionally
configured to compute the indication of a reduction of blood supply
to at least a portion of the heart using the PAP signal, the
different physiological signal, and at least one weighting factor
for the PAP signal or the different physiological signal.
[0022] In Example 17, the at least one weighting factor for the PAP
signal or the different physiological signal of Examples 1-16
optionally includes at least one of a signal-to-noise ratio ("SNR")
and a performance metric, wherein the performance metric includes
at least one of a sensitivity, a specificity, a positive prediction
value ("PPV"), and a negative prediction value ("NPV").
[0023] In Example 18, the processor of Examples 1-17 is optionally
configured to compute the indication of a reduction of blood supply
to at least a portion of the heart using a temporal profile,
wherein the temporal profile includes using the PAP information and
information from the different physiological signal in a sequential
manner.
[0024] In Example 19, the system of Examples 1-18 optionally
includes an implantable respiration sensor, configured to sense a
respiration signal, and an implantable or external respiration
phase detector, coupled to the respiration sensor, configured to
detect at least one phase of the respiration signal. The processor
of Examples 1-18 is also optionally communicatively coupled to the
respiration phase detector to receive respiration information. The
processor is also optionally configured to use the PAP information
and the respiration information to compute the indication of the
reduction of blood supply to at least a portion of the heart,
including at least one of the processor being configured to form a
composite signal using at least a portion of the PAP signal over at
least a portion of the at least one phase of the respiration
signal, the processor being configured to obtain a gated PAP signal
using information from the respiration phase detector, and the
processor being configured to enable or disable the PA pressure
sensor during at least a portion of at least one phase of the
respiration signal.
[0025] In Example 20, a system includes means for chronically
implantably sensing a pulmonary artery pressure ("PAP") signal of a
pulmonary artery ("PA"), such as by using a PA pressure sensor to
sense the PAP signal of the PA. The system also includes means for
using the PAP signal to compute an indication of a reduction of
blood supply to at least a portion of a heart, such as by using a
processor to detect a change in the PAP, using the processor to
detect a deviation from a baseline, etc.
[0026] In Example 21, a method includes chronically implantably
sensing a pulmonary artery pressure ("PAP") signal of a pulmonary
artery ("PA"). The method also includes using the PAP signal for
computing an indication of a reduction of blood supply to at least
a portion of a heart.
[0027] In Example 22, the sensing of Example 21 optionally includes
using an implantable chronic PA pressure sensor configured to be
fixed within the PA.
[0028] In Example 23, the using the PAP signal of Examples 21-22
optionally includes using a change in the PAP.
[0029] In Example 24, the method of Examples 21-23 optionally
includes detecting at least one feature of the PAP signal. The
method also optionally includes detecting at least one interval
between the at least one feature of the PAP signal occurring at a
first time and the at least one feature of the PAP signal occurring
at a second time: The computing the indication of a reduction of
blood supply to at least a portion of the heart of Examples 21-23
optionally includes using information from the at least one
interval between the at least one feature of the PAP signal
occurring at a first time and the at least one feature of the PAP
signal occurring at a second time.
[0030] In Example 25, the computing the indication of a reduction
of blood supply to at least a portion of the heart of Examples
21-24 optionally includes using at least one measurement
correlative to at least one of a change in left ventricle ("LV")
pressure, a change in LV diastolic pressure, a change in LV volume,
and a rate of pressure change in the LV ("LV dP/dt").
[0031] In Example 26, the computing the indication of a reduction
of blood supply to at least a portion of the heart of Examples
21-25 optionally includes using a detected change in a PA pressure
characteristic, where the PA pressure characteristic includes at
least one of a PA diastolic ("PAD") pressure, a PA systolic ("PAS")
pressure, a mean PAP, and a rate of pressure change in the PA ("PA
dP/dt").
[0032] In Example 27, the computing the indication of a reduction
of blood supply to at least a portion of the heart of Examples
21-26 optionally includes using at least one measurement of the PAP
signal to compute an indication of a reduction of blood supply to a
myocardium of a left ventricle.
[0033] In Example 28, the computing the indication of a reduction
of blood supply to at least a portion of the heart of Examples
21-27 optionally includes comparing at least one measurement of the
PAP signal to a baseline.
[0034] In Example 29, the method of Examples 21-28 optionally
includes using the PAP signal for detecting an indication of mitral
valve performance. The computing the indication of a reduction of
blood supple to at least a portion of the heart of Examples 21-28
optionally includes using the detected indication of mitral valve
performance.
[0035] In Example 30, the method of Examples 21-29 optionally
includes sensing a different physiological signal, and computing
the indication of a reduction of blood supply to at least a portion
of the heart using the PAP signal and the different physiological
signal.
[0036] In Example 31, the sensing a different physiological signal
of Examples 21-30 optionally includes sensing a different
physiological signal that is indicative of a reduction of blood
supply to at least a portion of the heart.
[0037] In Example 32, the method of Examples 21-31 optionally
includes detecting at least one feature of the different
physiological signal, detecting at least one feature of the PAP
signal, and detecting at least one interval between the at least
one different physiological signal feature and the at least one PAP
signal feature. The computing the indication of a reduction of
blood supply to at least a portion of the heart optionally includes
using the at least one interval between the at least one different
physiological signal feature and the at least one PAP signal
feature.
[0038] In Example 33, the sensing a different physiological signal
of Examples 21-32 optionally includes sensing a cardiac signal as
the different physiological signal.
[0039] In Example 34, the sensing the different physiological
signal of Examples 21-33 optionally includes sensing a heart sound
signal as the different physiological signal.
[0040] In Example 35, the sensing the different physiological
signal of Examples 21-34 optionally includes sensing at least one
of a right ventricular pressure signal, a left ventricular pressure
signal, a blood pressure signal, and an oxygen saturation signal as
the different physiological signal.
[0041] In Example 36, the computing the indication of a reduction
of blood supply to at least a portion of the heart of Examples
21-35 optionally includes using the PAP signal, the different
physiological signal, and at least one weighting factor for the PAP
signal or the different physiological signal.
[0042] In Example 37, the using the at least one weighting factor
for the PAP signal or the different physiological signal of
Examples 21-36 optionally includes using at least of a
signal-to-noise ratio ("SNR") and a performance metric, wherein
using the performance metric includes using at least one of a
sensitivity, a specificity, a positive prediction value ("PPV"),
and a negative prediction value ("NPV").
[0043] In Example 38, the computing the indication of a reduction
of blood supply to at least a portion of the heart of Examples
21-37 optionally includes using a temporal profile, wherein using
the temporal profile includes using the PAP signal and the
different physiological signal in a sequential manner.
[0044] In Example 39, the method of Examples 21-38 optionally
includes sensing a respiration signal, detecting at least a portion
of at least one phase of the respiration signal, and using the PAP
signal and respiration signal information for computing the
indication of the reduction of blood supply to at least a portion
of the heart. The computing the indication of the reduction of
blood supply to at least a portion of the heart of Examples 21-38
also optionally includes at least one of forming a composite signal
using at least a portion of the PAP signal over at least a portion
of at least one phase of the respiration signal, obtaining a gated
PAP signal using information from the respiration signal, and
enabling or disabling the sensing the PAP signal using at least a
portion of at least one phase of the respiration signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In the drawings, which are not necessarily drawn to scale,
like numerals describe substantially similar components throughout
the several views. Like numerals having different letter suffixes
represent different instances of substantially similar components.
The drawings illustrate generally, by way of example, but not by
way of limitation, various embodiments discussed in the present
document.
[0046] FIG. 1 illustrates generally an example of a system
including a PA pressure sensor and a processor.
[0047] FIG. 2 illustrates generally an example of a system
including a heart, a PA pressure sensor, and a PA.
[0048] FIG. 3 illustrates generally an example of a system
including a PA pressure sensor, a processor, and an auxiliary
physiological sensor.
[0049] FIG. 4 illustrates generally an example of a system
including a PA pressure sensor, a processor, and a cardiac
sensor.
[0050] FIG. 5 illustrates generally an example of a system
including a PA pressure sensor, a processor, and a heart sound
sensor.
[0051] FIG. 6 illustrates generally an example of a system
including a PA pressure sensor, a processor, a right ventricular
pressure sensor, a left ventricular pressure sensor, a blood
pressure sensor, and an oxygen saturation sensor.
[0052] FIG. 7 illustrates generally an example of a system
including a PA pressure sensor, a processor, a respiration sensor,
and a respiration phase detector.
[0053] FIG. 8 illustrates generally an example of a relationship
between LVEDP and PA end-diastolic pressure ("PAEDP"), including a
regression line.
[0054] FIG. 9 illustrates generally an example of LVEDP during
balloon inflation and deflation and the rate of pressure change in
the LV ("LV dP/dt") during balloon inflation and deflation.
[0055] FIG. 10 illustrates generally an example of a method
including sensing a PAP signal and computing an indication of a
reduction of blood supply to at least a portion of a heart.
[0056] FIG. 11 illustrates generally an example of a method
including sensing a PAP signal, detecting at least one feature of
the PAP signal, detecting at least one interval between the at
least one feature of the PAP signal occurring at a first time and
the at least one feature of the PAP signal occurring at a second
time, and computing an indication of a reduction of blood supply to
at least a portion of a heart using the at least one interval.
[0057] FIG. 12 illustrates generally an example of a method
including sensing a PAP signal, detecting an indication of mitral
valve performance using the PAP signal, and computing an indication
of a reduction of blood supply to at least a portion of a heart
using the detected mitral valve performance.
[0058] FIG. 13 illustrates generally an example of a method
including sensing a PAP signal, sensing a different physiological
signal, and computing an indication of a reduction of blood supply
to at least a portion of a heart using the PAP signal and the
different physiological signal.
[0059] FIG. 14 illustrates generally an example of a method
including sensing a PAP signal, detecting at least one feature of
the PAP signal, sensing a different physiological signal, detecting
at least one feature of the different physiological signal,
detecting at least one interval between the at least one different
physiological signal feature and the at least one PAP signal
feature, and computing an indication of a reduction of blood supply
to at least a portion of a heart using the at least one
interval.
[0060] FIG. 15 illustrates generally an example of a method
including sensing a PAP signal, sensing a respiration signal,
detecting at least a portion of at least one phase of the
respiration signal, forming a composite signal using at least a
portion of the PAP signal over at least a portion of at least one
phase of the respiration signal, obtaining a gated PAP signal using
information from the respiration signal, enabling or disabling the
sensing the PAP signal using at least a portion of at least one
phase of the respiration signal, and computing an indication of a
reduction of blood supply to at least a portion of a heart.
DETAILED DESCRIPTION
[0061] The following detailed description includes references to
the accompanying drawings, which form a part of the detailed
description. The drawings show, by way of illustration, specific
embodiments in which the invention may be practiced. These
embodiments, which are also referred to herein as "examples," are
described in enough detail to enable those skilled in the art to
practice the invention. The embodiments may be combined, other
embodiments may be utilized, or structural, logical and electrical
changes may be made without departing from the scope of the present
invention. The following detailed description is, therefore, not to
be taken in a limiting sense, and the scope of the present
invention is defined by the appended claims and their
equivalents.
[0062] In this document, the terms "a" or "an" are used, as is
common in patent documents, to include one or more than one. In
this document, the term "or" is used to refer to a nonexclusive or,
such that "A or B" includes "A but not B," "B but not A," and "A
and B," unless otherwise indicated. Furthermore, all publications,
patents, and patent documents referred to in this document are
incorporated by reference herein in their entirety, as though
individually incorporated by reference. In the event of
inconsistent usages between this document and those documents so
incorporated by reference, the usage in the incorporated
reference(s) should be considered supplementary to that of this
document; for irreconcilable inconsistencies, the usage in this
document controls.
[0063] Generally, when at least 25% of the myocardium of the LV
becomes acutely ischemic, the LVEDP and LV volume increase.
Typically, in an acute coronary occlusion event, the LVEDP can
increase by 10 mmHg and the rate of pressure change in the LV ("LV
dP/dt") can decrease by 500 mmHg/s in less than one minute.
[0064] During diastole, the PA diastolic pressure generally
correlates to LVEDP. Thus, the change in LVEDP during a reduction
of blood supply to the myocardium of the LV can typically be
detected using the PA diastolic pressure. A reduction of blood
supply, such as ischemia or myocardial infarction, to at least a
portion of a heart, such as the myocardium of the LV, can generally
be detected using information from an implantable PA pressure
sensor. Using an implantable PA pressure sensor can allow for
detection of a reduction of blood supply to at least a portion of
the heart even before the subject undergoes symptoms of ischemia or
myocardial infarction, or in asymptomatic subjects. Using an
implantable PA pressure sensor can also typically allow for an
enhanced detection ability by using the PA sensor information as
well as other sensor information, such as a cardiac sensor
information, a respiration sensor information, a right ventricle
("RV") pressure sensor information, a LV pressure sensor
information, a blood pressure sensor information, and an oxygen
saturation sensor information, and separately can generally allow
for trending capability. Further, using a non-lead-based PA
pressure sensor can generally be advantageous for chronic
monitoring of PA pressure.
[0065] FIG. 1 illustrates generally an example of a system 100
including a PA pressure sensor 105 and a processor 110. The PA
pressure sensor 105 generally includes an implantable PA pressure
sensor, configured to be located in a PA of a subject. In certain
examples, the processor 110 can be an implantable component, an
external component, or a combination or permutation of an
implantable component and an external component.
[0066] Generally, the PA pressure sensor 105 can be configured to
sense a pulmonary artery pressure ("PAP") signal of the PA of the
subject. The PAP signal can include any signal indicative of the
PAP of the PA of the subject. The PA pressure sensor 105 can be
configured to produce a PAP signal, such as an electrical or
optical PAP signal, that includes information about the PAP of the
PA of the subject. The PA pressure sensor 105 can include a chronic
PA pressure sensor, configured to remain in the PA for a continuing
or extended period of time.
[0067] In the example of FIG. 1, the PA pressure sensor 105 can
include a chronic non-lead-based pressure sensor. In certain
examples, the non-lead-based pressure sensor can be implemented as
a stand-alone device. The non-lead-based pressure sensor can be
implemented with or without another implantable medical device,
such as a pacemaker, defibrillator, or other implantable medical
device, or the non-lead-based pressure sensor can be configured to
be located at a close proximity to the left side of the heart, such
as within the PA, to receive a physiologic signal at a close
proximity to the left side of the heart.
[0068] In an example, the PA pressure sensor 105 can include a
sensor, such as a pressure sensor, being implantable in a blood
vessel supporting blood into or out of a cavity of a heart, such as
a pulmonary artery, an example of which is disclosed in the Porat
et al. U.S. Pat. No. 6,278,078 entitled "SYSTEM AND METHOD FOR
MONITORING A PARAMETER ASSOCIATED WITH THE PERFORMANCE OF A HEART,"
(herein "Porat et al. '078") assigned to Remon Medical
Technologies, Ltd. A PA pressure sensor can be used for monitoring
a parameter associated with the performance of the heart, including
collecting information pertaining to a pressure and a flow within
the blood vessel supporting blood into or out of the cavity of the
heart, such as the pulmonary artery. A separate sensor, such as a
pressure sensor, can be used within the heart for collecting
information pertaining to a pressure in a first cavity of the
heart, such as a ventricle, and processing and interpreting
information from both sensors to yield information pertaining to
the heart performance of a subject.
[0069] In another example, the PA pressure sensor 105 can include
an implantable pressure sensor placed in the PA to sense the PAP
signal, such as that disclosed in the commonly assigned Stahmann
U.S. patent application Ser. No. 11/249,624 entitled "METHOD AND
APPARATUS FOR PULMONARY ARTERY PRESSURE SIGNAL ISOLATION," which is
hereby incorporated by reference in its entirety, including its
disclosure of sensing the PAP signal using the implantable pressure
sensor placed in the PA. In other examples, other pressure sensor
configurations can be used to sense the PAP signal.
[0070] The PA pressure sensor 105 can be configured to communicate
with one or more than one implantable medical device ("IMD"), such
as the processor 110, a cardiac rhythm management device, an
external medical device, or a combination or permutation of the one
or more than one IMD, the processor 110, the cardiac rhythm
management device, and the external medical device. Certain
examples of such sensors, sensor configurations, and communication
systems and methods are discussed in more detail in the Mazar et
al. U.S. patent application Ser. No. 10/943,626 entitled "SYSTEMS
AND METHODS FOR DERIVING RELATIVE PHYSIOLOGIC PARAMETERS;" the Von
Arx et al. U.S. patent application Ser. No. 10/943,269 entitled
"SYSTEMS AND METHODS FOR DERIVING RELATIVE PHYSIOLOGIC MEASUREMENTS
USING AN EXTERNAL COMPUTING DEVICE;" the Von Arx et al. U.S. patent
application Ser. No. 10/943,627 entitled "SYSTEMS AND METHODS FOR
DERIVING RELATIVE PHYSIOLOGIC PARAMETERS USING A BACKEND COMPUTING
SYSTEM;" and the Chavan et al. U.S. patent application Ser. No.
10/943,271 entitled "SYSTEMS AND METHODS FOR DERIVING RELATIVE
PHYSIOLOGIC PARAMETERS USING AN IMPLANTED SENSOR DEVICE;" and the
U.S. patent application Ser. No. 10/943,271 entitled "SYSTEMS AND
METHODS FOR DERIVING RELATIVE PHYSIOLOGIC MEASUREMENTS USING AN
IMPLANTED SENSOR DEVICE," all assigned to Cardiac Pacemakers, Inc.,
all of which are incorporated herein by reference in their
entirety, and which are collectively referred to as the
"Physiologic Parameter Sensing Systems and Methods Patents" in this
document.
[0071] In the example of FIG. 1, the processor 110 can be
communicatively coupled to the PA pressure sensor 105. The
processor 110 can be configured to receive information from the PA
pressure sensor 105, such as discussed in more detail in the
Physiologic Parameter Sensing Systems and Methods Patents.
Generally, the processor 110 can be configured to compute an
indication of a reduction of blood supply, such as ischemia or
myocardial infarction, to at least a portion of a heart, such as
the myocardium of the left ventricle or other portion of the heart.
This may involve using information from the PA pressure sensor 105,
such as by using at least one detected PA pressure characteristic
or other information from the PA pressure sensor 105.
[0072] In an example, the processor 110 can be configured to detect
at least one PA pressure characteristic, such as a PA diastolic
pressure ("PAD"), a PA systolic pressure ("PAS"), a mean (or other
central tendency) PAP, a PA end-diastolic pressure ("PAEDP"), a
rate of pressure change in the PA ("PA dP/dt"), a PA pulse pressure
("PAPP"), or other PA pressure characteristic, using PAP
information, such as the PAP signal, from the PA pressure sensor
105. The processor 110 can be configured to compute an indication
of a reduction of blood supply to at least a portion of the heart
using the at least one detected PA pressure characteristic, such as
by using at least one detected feature of the at least one detected
PA pressure characteristic. The at least one detected feature of
the at least one detected PA pressure characteristic can include at
least one of at least one detected amplitude, at least one detected
magnitude, at least one detected peak, at least one detected
valley, at least one detected value, at least one detected change,
at least one detected increase, at least one detected decrease, and
at least one detected rate of change in the at least one PA
pressure characteristic. In another example, the processor 110 can
be configured to compute an indication of a reduction of blood
supply to at least a portion of the heart using a combination or
permutation of the at least one detected PA pressure
characteristics or features.
[0073] In another example, the processor 110 can be configured to
detect at least one signal correlative to at least one LV pressure
characteristic, such as a LV pressure, a LV diastolic pressure, a
LV systolic pressure, a LVEDP, a mean (or other central tendency)
LV pressure, a LV volume, a LV dP/dt, or other LV pressure
characteristic, using PAP information from the PA pressure sensor
105. The processor 110 can be configured to compute an indication
of a reduction of blood supply to at least a portion of the heart
using the at least one signal correlative to at least one LV
pressure characteristic, such as by using at least one detected
feature of the at least one detected signal correlative to the at
least one LV pressure characteristic. The at least one detected
feature of the at least one detected signal correlative to the at
least one LV pressure characteristic can include at least one of at
least one detected amplitude, at least one detected magnitude, at
least one detected peak, at least one detected valley, at least one
detected value, at least one detected change, at least one detected
increase, at least one detected decrease, and at least one detected
rate of change in the at least one detected signal correlative to
at least one LV pressure characteristic. In another example, the
processor 110 can be configured to compute an indication of a
reduction of blood supply to at least a portion of the heart using
a combination or permutation of the at least one detected signal
correlative to at least one LV pressure characteristic or the at
least one detected feature of such signal.
[0074] In the example of FIG. 1, the processor 110 can include a
time interval detector. In an example, the time interval detector
can be configured to detect at least one time interval between at
least a first feature of the PAP signal occurring at a first time
and at least a second feature of the PAP signal occurring at a
second time. In certain examples, the processor 110 can be
configured to compute one or more than one output, such as by using
at least one mathematical operation and one or more than one
interval, such as computing the difference between more than one
interval, computing an average of more than one interval, computing
an average of more than one interval, or computing one or more than
one other output using at least one mathematical operation and one
or more than one interval. In an example, the processor 110 can be
configured to compute the indication of a reduction of blood
supply, such as ischemia or myocardial infarction, to at least a
portion of the heart, such as the myocardium of the left ventricle
or other portion of the heart, using information from the at least
one interval between the at least one feature of the PAP signal
occurring at a first time and the at least one feature of the PAP
signal occurring at a second time.
[0075] In an example, the processor 110 can be configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart by comparing at least a portion of the PAP
information to a baseline. In certain examples, the baseline can
include at least one of a population-based baseline, a
subject-based baseline, an absolute baseline, and an adaptive
baseline. In an example, the population-based baseline can include
a condition-specific population-based baseline, such as a
population-based baseline for subjects having hypotension,
hypertension, heart failure, another condition, or one or more than
one combination or permutation of one or more than one condition.
In an example, the indication of a reduction of blood supply to at
least a portion of the heart can include at least a portion of the
PAP information, such as the PAP, the PAD, the PAS, the mean PAP,
the PA dP/dt, etc., meeting, exceeding, or deviating from the
baseline such as by a threshold amount. In another example, the
indication of a reduction of blood supply to at least a portion of
the heart can be computed using information from the difference
between at least a portion of the PAP information and the baseline.
In an example, the baseline can be established or reestablished
using the processor 110.
[0076] In another example, the processor 110 can be configured to
compute the indication of a reduction of blood supply to at least a
portion of the heart by comparing at least a portion of the at
least one measurement correlative to the at least one LV pressure
characteristic to a baseline. In an example, the indication of a
reduction of blood supply to at least a portion of the heart can
include at least a portion of the at least one measurement
correlative to the at least one LV pressure characteristic, such as
the LV pressure, the LV diastolic pressure, the LVEDP, the LV
systolic pressure, the mean LV pressure, the LV volume, the LV
dP/dt, etc., meeting, exceeding, or deviating from the baseline. In
another example, the indication of a reduction of blood supply to
at least a portion of the heart can be computed using information
from the difference between at least a portion of the at least one
measurement correlative to the at least one LV pressure
characteristic and the baseline.
[0077] In another example, the processor 110 can be configured to
detect an indication of mitral valve performance using the PAP
information. Generally, mitral valve performance can include any
indicator of mitral valve function or dysfunction, such as mitral
regurgitation ("MR"), mitral valve dysfunction, improper mitral
valve seat or closure, an abnormal or backward pressure
characteristic in a PAP signal or a LV pressure signal, etc.
Typically, an indicator of ischemia, myocardial infarction, or
other reduction in blood supply to the heart, can include mitral
valve performance, such as MR or other mitral valve dysfunction.
The processor 110 can be configured to compute an indication of a
reduction of blood supply to at least a portion of the heart using
the detected indication of mitral valve performance, such as
MR.
[0078] In another example, the processor 110 can be configured to
provide a notification of the computed indication of a reduction of
blood supply to at least a portion of the heart to an external
device, such as an external repeater, IMD, or other device capable
of communicating with the processor 110. In certain examples, the
external repeater, IMD, or other device can be configured to
communicate, such as by an e-mail or other communication, to a
user, such as a physician or other caregiver, or the subject.
[0079] FIG. 2 illustrates generally an example of a system 200
including a heart 101, a PA pressure sensor 105, and a PA 106.
Typically, the PA 106 of a subject carries blood from the RV of the
heart 101 to the lungs. In the example of FIG. 2, the PA pressure
sensor 105 is located in the PA 106 of the subject. The PA pressure
sensor 105 can be fixed to a location within the PA 106, such as
fixed to a wall of the PA 106. In an example, the PA pressure
sensor 105 can be fixed to a location within the PA 106 without
requiring a catheter, lead, or other component, to hold the PA
pressure sensor 105 in the PA 106 of the subject.
[0080] In the example of FIG. 2, the PA pressure sensor 105 can be
delivered, positioned, or anchored in a PA 106 of a subject, such
as disclosed in the commonly assigned Chavan et al. U.S. patent
application Ser. No. 11/216,738 entitled "DEVICES AND METHODS FOR
POSITIONING AND ANCHORING IMPLANTABLE SENSOR DEVICES," (herein
"Chavan et al. '738") which is hereby incorporated by reference in
its entirety, including its disclosure of delivering, positioning,
and anchoring a physiologic parameter sensor, such as a pressure
sensor, to a bodily vessel, such as the pulmonary artery. In other
examples, other methods of delivering, positioning, or anchoring
physiologic parameter sensors can be used.
[0081] FIG. 3 illustrates generally an example of a system 300
including a PA pressure sensor 105, a processor 110, and an
auxiliary physiological sensor 115. In certain examples, one or
more of the PA pressure sensor 105, the processor 110, or the
auxiliary physiological sensor 115, can be an implantable
component, an external component, or a combination or permutation
of an implantable component and an external component. For example,
the processor 110 may be implantable, external, or distributed
across both implantable and external locations.
[0082] Generally, the auxiliary physiological sensor 115 can be
configured to sense a different physiological signal of a subject,
such as a physiological signal other than the PAP signal of the
subject. The auxiliary physiological sensor 115 can include an
implantable or external sensor configured to sense a different
physiological signal of the subject, such as a cardiac sensor 116
(as shown in FIG. 4 below) configured to sense a cardiac signal of
the subject, a heart sound sensor 117 (as shown in FIG. 5 below)
configured to sense a heart sound signal of the subject, a right
ventricular pressure sensor 118 (as shown in FIG. 6 below)
configured to sense a right ventricular pressure signal of the
subject, a left ventricular pressure sensor 119 (as shown in FIG.
6) configured to sense a left ventricular pressure signal of the
subject, a blood pressure sensor 120 (as shown in FIG. 6)
configured to sense a blood pressure signal of the subject, an
oxygen saturation sensor 121 (as shown in FIG. 6) configured to
sense an oxygen saturation signal of the subject, an impedance
sensor to sense a cardiac impedance of the subject, an
accelerometer, such as a lead based accelerometer, to sense an
acceleration or deceleration of the subject, such as an
acceleration or deceleration of the left ventricle of the subject,
an activity sensor configured to sense an activity signal of the
subject, a posture sensor configured to sense a posture of a
subject, or other auxiliary physiological sensor configured to
sense another physiological signal of the subject. Generally, the
different physiological signal includes a physiological signal
indicative of a reduction of blood supply to at least a portion of
the heart, such as a cardiac signal, a heart sound signal, etc.
[0083] In this example, the processor 110 can be communicatively
coupled to the auxiliary physiological sensor 115 and the PA
pressure sensor 105. The processor 110 can be configured to receive
information from the auxiliary physiological sensor 115, such as
the different physiological signal, and information from the PA
pressure sensor 105, such as the PAP signal. In an example, the
processor 110 can be configured to compute an indication of a
reduction of blood supply to at least a portion of the heart using
information from the PA pressure sensor 105 and information from
the auxiliary physiological sensor 115, such as the different
physiological signal.
[0084] In the example of FIG. 3, the processor 1 10 can be
configured to detect at least one feature of the different
physiological signal, such as at least one of at least one detected
amplitude, at least one detected magnitude, at least one detected
peak, at least one detected valley, at least one detected value, at
least one detected change, at least one detected increase, at least
one detected decrease, and at least one detected rate of change in
the different physiological signal.
[0085] The processor 110 can also include a time interval detector.
In an example, the time interval detector can be configured to
detect at least one interval between the at least one different
physiological signal feature occurring at a first time and at least
one PAP signal feature occurring at a second time. In certain
examples, the processor 110 can be configured to compute one or
more than one output using at least one mathematical operation and
one or more than one interval, such as computing the difference
between more than one interval, computing an average of more than
one interval, computing a ratio of more than one interval, or
computing other outcomes using at least one mathematical operation
and one or more than one interval. In an example, the processor 110
can be configured to compute the indication of a reduction of blood
supply to at least a portion of the heart using the at least one
interval between the at least one different physiological signal
feature occurring at the first time and the at least one PAP signal
feature occurring at the second time.
[0086] FIG. 4 illustrates generally an example of a system 400
including a PA pressure sensor 105, a processor 110, and a cardiac
sensor 116. In certain examples, the PA pressure sensor 105, the
processor 110, or the cardiac sensor 116, can be an implantable
component, an external component, or a combination or permutation
of an implantable component and an external component, such as
described above.
[0087] Generally, the cardiac sensor 116 can be configured to sense
a cardiac signal of a subject. The cardiac signal can include any
signal indicative of the electrical or mechanical cardiac activity
of the heart, e.g., an electrocardiogram ("ECG") signal, an
impedance signal, an acceleration signal, etc. The cardiac sensor
116 can be configured to produce a cardiac signal, such as an
electrical or optical cardiac signal, that includes information
about the cardiac signal of the subject. The cardiac sensor 116 can
include any device configured to sense the cardiac activity of the
subject. In certain examples, the cardiac sensor 116 can include an
intrinsic cardiac signal sensor, such as one or more than one
electrode or lead to sense one or more than one depolarization, or
a mechanical sensor, such as an impedance sensor or an
accelerometer to sense one or more than one contraction.
[0088] In this example, the processor 110 can be communicatively
coupled to the cardiac sensor 116 and the PA pressure sensor 105.
The processor 110 can be configured to receive information from the
cardiac sensor 116, such as the cardiac signal, and information
from the PA pressure sensor 105, such as the PAP signal. In an
example, the processor 110 can be configured to detect at least one
feature of the cardiac signal. Typically, the at least one cardiac
signal feature can include at least one feature or component of an
ECG signal, e.g., at least one component of a P-wave, at least one
component of a Q-wave, at least one component of a R-wave, at least
one component of a S-wave, at least one component of a T-wave, or
any combination or permutation of features or components of the ECG
signal, or any mechanical cardiac features of a pressure signal or
acceleration signal indicative of the cardiac activity of a
subject.
[0089] In the example of FIG. 4, the processor 110 can be
configured to compute an indication of a reduction of blood supply
to at least a portion of the heart using information from the PA
pressure sensor 105, such as the PAP signal, and information from
the cardiac sensor 116, such as the cardiac signal, at least one
detected feature of the cardiac signal, etc.
[0090] FIG. 5 illustrates generally an example of a system 500
including a PA pressure sensor 105, a processor 110, and a heart
sound sensor 117. In certain examples, the PA pressure sensor 105,
the processor 110, or the heart sound sensor 117, can be an
implantable component, an external component, or a combination or
permutation of an implantable component and an external
component.
[0091] Generally, the heart sound sensor 117 can be configured to
sense a heart sound signal of a subject. The heart sound signal can
include any signal indicative of at least a portion of at least one
heart sound of the subject. A heart sound of the subject can
include an audible or mechanical noise or vibration indicative of
blood flow through the heart or valve closures of the heart. The
heart sound sensor 117 can be configured to produce a heart sound
signal, such as an electrical or optical heart sound signal, that
includes information about the heart sound signal of the subject.
The heart sound sensor 117 can include any device configured to
sense the heart sound signal of the subject. In certain examples,
the heart sound sensor 117 can include an implantable sensor
including at least one of an accelerometer, an acoustic sensor, a
microphone, etc.
[0092] In an example, the heart sound sensor 117 can include an
accelerometer configured to sense an acceleration signal indicative
of the heart sound of the subject, such as that disclosed in the
commonly assigned Carlson et al. U.S. Pat. No. 5,792,195 entitled
"ACCELERATION SENSED SAFE UPPER RATE ENVELOPE FOR CALCULATING THE
HEMODYNAMIC UPPER RATE LIMIT FOR A RATE ADAPTIVE CARDIAC RHYTHM
MANAGEMENT DEVICE," which is hereby incorporated by reference in
its entirety, including its disclosure of accelerometer detection
of heart sounds, or such as that disclosed in the commonly assigned
Siejko et al. U.S. patent application Ser. No. 10/334,694, entitled
"METHOD AND APPARATUS FOR MONITORING OF DIASTOLIC HEMODYNAMICS,"
(herein "Siejko et al. '694"), which is hereby incorporated by
reference in its entirety, including its disclosure of
accelerometer detection of heart sounds. In other examples, other
accelerometer or acceleration sensor configurations can be used to
sense the heart sound signal.
[0093] In another example, the heart sound sensor 117 can include
an acoustic sensor configured to sense an acoustic energy
indicative of the heart sound of the subject, such as that
disclosed in the commonly assigned Siejko et al. '694, incorporated
by reference in its entirety, including its disclosure of acoustic
sensing of heart sounds. In other examples, other acoustic sensor
or microphone configurations can be used to sense the heart sound
signal.
[0094] In this example, the processor 110 can be communicatively
coupled to the heart sound sensor 117 and the PA pressure sensor
105. The processor 110 can be configured to receive information
from the heart sound sensor 117, such as the heart sound signal,
and information from the PA pressure sensor 105, such as the PAP
signal. In an example, the processor 110 can be configured to
detect at least one measurement, feature, characteristic,
computation, or interval of at least a portion of at least one
heart sound. In certain examples, this includes at least one of an
amplitude of a heart sound, a magnitude of a heart sound, a total
energy of a heart sound, an interval between one heart sound
feature and another heart sound feature, at least one heart sound
characteristic normalized by at least one other heart sound
characteristic, etc. (e.g., an amplitude or magnitude of S1, an
amplitude or magnitude of S2, an amplitude or magnitude of S3, an
amplitude or magnitude of S4, the existence of a split-S2, a
split-S2 time interval, a time interval between S1 and S2 ("S1-S2
time interval"), a time interval between S2 and S3 ("S2-S3 time
interval"), a characteristic of S3 normalized by a characteristic
of S1, etc.).
[0095] In the example of FIG. 5, the processor 110 can be
configured to compute an indication of a reduction of blood supply
to at least a portion of the heart using information from the PA
pressure sensor 105, such as the PAP signal, and information from
the heart sound sensor 117, such as the heart sound signal, at
least one detected measurement, feature, characteristic,
computation, or interval of at least a portion of at least one
heart sound, etc.
[0096] In an example, an indication of a reduction of blood supply
to at least a portion of the heart can be computed using a
subsequent change in the heart sound signal from an established
baseline heart sound signal, such as that disclosed in the commonly
assigned Zhang et al. U.S. patent application Ser. No. 11/148,107
entitled "ISCHEMIA DETECTION USING HEART SOUND SENSOR," which is
hereby incorporated by reference in its entirety, including its
disclosure of deeming that an ischemic event has occurred using a
measured subsequent change in the heart sound signal from an
established baseline heart sound signal.
[0097] FIG. 6 illustrates generally an example of a system 600
including a PA pressure sensor 105, a processor 110, a right
ventricular pressure sensor 118, a left ventricular pressure sensor
119, a blood pressure sensor 120, and an oxygen saturation sensor
121. In certain examples, the PA pressure sensor 105, the processor
110, the right ventricular pressure sensor 118, the left
ventricular pressure sensor 119, the blood pressure sensor 120, or
the oxygen saturation sensor 121, can be an implantable component,
an external component, or a combination or permutation of an
implantable component and an external component.
[0098] In an example, the right ventricular pressure sensor 118 can
be configured to sense a right ventricular pressure signal of a RV
of a subject. The right ventricular pressure signal can include any
signal indicative of the right ventricular pressure of the RV of
the subject. The right ventricular pressure sensor 118 can be
configured to produce a right ventricular pressure signal, such as
an electrical or optical right ventricular pressure signal, that
includes information about the right ventricular pressure of the RV
of the subject.
[0099] In certain examples, the right ventricular pressure sensor
118 can include an implantable sensor, such as an implantable
solid-state pressure transducer disposed on a catheter or an
electrical lead, such as that disclosed in the commonly assigned
Ding et al. U.S. Pat. No. 6,280,389 entitled "PATIENT
IDENTIFICATION FOR THE PACING THERAPY USING LV-RV PRESSURE LOOP,"
(herein "Ding et al. '389") which is hereby incorporated by
reference in its entirety, including its disclosure of measuring
right ventricular pressure using a solid-state pressure transducer
disposed on a catheter or an electrical lead, or at least one
pressure transducer at a distal end, such as that disclosed in the
commonly assigned Salo et al. U.S. Pat. No. 6,666,826 entitled
"METHOD AND APPARATUS FOR MEASURING LEFT VENTRICULAR PRESSURE,"
(herein "Salo et al. '826") which is hereby incorporated by
reference in its entirety, including its disclosure of attaching a
pressure transducer to a catheter that is disposed within an open
lumen of a lead system. In other examples, other pressure sensor
configurations can be used to sense the right ventricular pressure
signal.
[0100] In this example, the processor 110 can be communicatively
coupled to the right ventricular pressure sensor 118 and the PA
pressure sensor 105. The processor 110 can be configured to receive
information from the right ventricular pressure sensor 118, such as
the right ventricular pressure signal, and information from the PA
pressure sensor 105, such as the PAP signal. In an example, the
processor 110 can be configured to compute an indication of a
reduction of blood supply to at least a portion of the heart using
information from the PA pressure sensor 105 and information from
the right ventricular pressure sensor 118.
[0101] In an example, the left ventricular pressure sensor 119 can
be configured to sense a left ventricular pressure signal of a LV
of the subject. The left ventricular pressure signal can include
any signal indicative of the left ventricular pressure of the LV of
the subject. The left ventricular pressure sensor 119 can be
configured to produce a left ventricular pressure signal, such as
an electrical or optical left ventricular pressure signal, that
includes information about the left ventricular pressure of the LV
of the subject.
[0102] In certain examples, the left ventricular pressure sensor
119 can include an implantable solid-state pressure transducer
disposed on a catheter or an electrical lead, such as that
disclosed in the commonly assigned Ding et al. '389, incorporated
by reference in its entirety, including its disclosure of measuring
left ventricular pressure using a solid-state pressure transducer
disposed on a catheter or an electrical lead, or at least one
pressure transducer at a distal end, such as that disclosed in the
commonly assigned Salo et al. '826, incorporated by reference in
its entirety, including its disclosure of attaching a pressure
transducer to a catheter that is disposed within an open lumen of a
lead system. In other examples, other pressure sensor
configurations can be used to sense the left ventricular pressure
signal.
[0103] In this example, the processor 110 can be communicatively
coupled to the left ventricular pressure sensor 119 and the PA
pressure sensor 105. The processor 110 can be configured to receive
information from the left ventricular pressure sensor 119, such as
the left ventricular pressure signal, and information from the PA
pressure sensor 105, such as the PAP signal. In an example, the
processor 110 can be configured to compute an indication of a
reduction of blood supply to at least a portion of the heart using
information from the PA pressure sensor 105 and information from
the left ventricular pressure sensor 119.
[0104] In an example, the blood pressure sensor 120 can be
configured to sense a blood pressure signal of the subject. The
blood pressure signal can include an arterial blood pressure
signal, an aortic blood pressure, a specific blood pressure signal,
such as a LVEDP signal, or other blood pressure signal. The blood
pressure sensor 120 can be configured to produce a blood pressure
signal, such as an electrical or optical blood pressure signal,
that includes information about the blood pressure of the
subject.
[0105] In this example, the processor 110 can be communicatively
coupled to the blood pressure sensor 120 and the PA pressure sensor
105. The processor 110 can be configured to receive information
from the blood pressure sensor 120, such as the blood pressure
signal, and information from the PA pressure sensor 105, such as
the PAP signal. In an example, the processor 110 can be configured
to compute an indication of a reduction of blood supply to at least
a portion of the heart using information from the PA pressure
sensor 105 and information from the blood pressure sensor 120.
[0106] In an example, the oxygen saturation sensor 121 can be
configured to sense an oxygen saturation signal of the subject. The
oxygen saturation signal can include any signal indicative of the
level of oxygen in the blood. The oxygen saturation sensor 121 can
be configured to produce an oxygen saturation signal, such as an
electrical or optical oxygen saturation signal, that includes
information about the level of oxygen in the blood of the
subject.
[0107] In this example, the processor 110 can be communicatively
coupled to the oxygen saturation sensor 121 and the PA pressure
sensor 105. The processor 110 can be configured to receive
information from the oxygen saturation sensor 121, such as the
oxygen saturation signal, and information from the PA pressure
sensor 105, such as the PAP signal. Generally, a reduction in blood
supply to at least a portion of the heart can result in a reduced
oxygen level to the at least a portion of the heart. In certain
examples, if the level of oxygen in the blood meets, exceeds, or
deviates from an established baseline, such as by a threshold
amount, an indication of a reduction of blood supply to at least a
portion of the heart can be computed. In an example, the processor
110 can be configured to compute an indication of a reduction of
blood supply to at least a portion of the heart using information
from the PA pressure sensor 105 and information from the oxygen
saturation sensor 121.
[0108] FIG. 7 illustrates generally an example of a system 700
including a PA pressure sensor 105, a processor 110, a respiration
sensor 125, and a respiration phase detector 130. In certain
examples, the PA pressure sensor 105, the processor 110, the
respiration sensor 125, or the respiration phase detector 130, can
be an implantable component, an external component, or a
combination or permutation of an implantable component and an
external component. In another example, some or all of the
functionality of the respiration phase detector 130 can be
implemented in the processor 110.
[0109] In this example, the respiration sensor 125 can be
configured to sense a respiration signal of a subject. The
respiration signal can include any signal indicative of the
respiration of the subject, such as inspiration, expiration, or any
combination, permutation, or component of the respiration of the
subject. The respiration sensor 125 can be configured to produce a
respiration signal, such as an electrical or optical respiration
signal, that includes information about the respiration of the
subject. In certain examples, the respiration sensor 125 can
include an implantable sensor including at least one of an
accelerometer, an impedance sensor, and a pressure sensor.
[0110] In an example, the respiration sensor 125 can include an
accelerometer configured to sense an acceleration signal indicative
of a cyclical variation indicative of respiration, such as that
disclosed in the commonly assigned Kadhiresan et al. U.S. Pat. No.
5,974,340 entitled "APPARATUS AND METHOD FOR MONITORING REPSIRATORY
FUNCTION IN HEART FAILURE PATIENTS TO DETERMINE EFFICACY OF
THERAPY," (herein "Kadhiresan et al. '340") which is hereby
incorporated by reference in its entirety, including its disclosure
of using an accelerometer to detect respiration. In another
example, the respiration sensor 125 can include a vibration sensor,
such as that disclosed in the commonly assigned Hatlestad et al.
U.S. Pat. No. 6,949,075 entitled "APPARATUS AND METHOD FOR
DETECTING LUNG SOUNDS USING AN IMPLANTED DEVICE," (herein
"Hatlestad et al. '075") which is hereby incorporated by reference
in its entirety, including its disclosure of using a vibration
sensor to detect respiration. In other examples, other
accelerometer configurations can be used to sense the respiration
signal.
[0111] In another example, the respiration sensor 125 can include
an impedance sensor configured to sense an impedance signal
indicative of respiration, such as that disclosed in the commonly
assigned Kadhiresan et al. '340, incorporated by reference in its
entirety. In another example, the respiration sensor 125 can
include a transthoracic impedance sensor, such as that disclosed in
the commonly assigned Hartley et al. U.S. Pat. No. 6,076,015
entitled "RATE ADAPTIVE CARDIAC RHYTHM MANAGEMENT DEVICE USING
TRANSTHROACIC IMPEDANCE," which is hereby incorporated by reference
in its entirety, including its disclosure of using a thoracic
impedance sensor to detect respiration. In other examples, other
impedance sensor configurations can be used to sense the
respiration signal.
[0112] In another example, the respiration sensor 125 can include a
pressure sensor configured to sense a pressure signal indicative of
respiration, such as that disclosed in the commonly assigned
Hatlestad et al. '075, incorporated by reference in its entirety,
including its disclosure of sensing a pressure signal indicative of
respiration. In other examples, other pressure sensor
configurations, such as a pulmonary artery pressure sensor, a
ventricular pressure sensor, a thoracic pressure sensor, etc., can
be used to sense a respiration signal.
[0113] In the example of FIG. 7, the respiration phase detector 130
can be coupled to the respiration sensor 125. The respiration phase
detector 130 can be configured to receive the respiration signal
from the respiration sensor 125. Generally, the respiration phase
detector 130 can be configured to detect at least a particular
portion of at least one phase of the respiration signal. In certain
examples, this includes at least portion of at least one of an
inspiration, an expiration, a transition between inspiration and
expiration, and a transition between expiration and
inspiration.
[0114] In this example, the processor 110 can be communicatively
coupled to the respiration phase detector 130 and the PA pressure
sensor 105. The processor 110 can be configured to receive
information from the respiration phase detector 130, such as the at
least a portion of at least one phase of the respiration signal,
and information from the PA pressure sensor 105, such as the PAP
signal.
[0115] In an example, the processor 110 can be configured to form a
composite signal, such as an average or other signal, using
information from the PA pressure sensor 105, such as at least a
portion of the PAP signal, and information from the respiration
phase detector 130, such as the at least a portion of the at least
one phase of the respiration signal. The processor 110 can be
configured to form an average signal using at least a portion of
the PAP signal over at least a portion of the at least one phase of
the respiration signal.
[0116] In another example, the processor 110 can be configured to
obtain a gated PAP signal, such as by gating the PAP signal using
information from the respiration phase detector 130. Typically, the
processor 110 can gate the PAP signal using at least one
respiration feature of the respiration signal to detect at least a
portion of the PAP signal occurring during at least a portion of at
least one phase of the respiration signal, such as the PAP signal
during at least a portion of inspiration, expiration, the
transition from inspiration to expiration or expiration to
inspiration, etc.
[0117] In another example, the processor 110 can be configured to
enable or disable the PA pressure sensor 105 during at least a
portion of at least one phase of the respiration signal using
information from the respiration phase detector 130. In certain
examples, the PA pressure sensor 105 can be enabled for a period of
time using information from the respiration phase detector 130,
such as being enabled for at least a portion of at least one
respiration phase or cycle every ten respiration phases or cycles,
being enabled for at least a portion of at least one respiration
phase or cycle every one hundred respiration phases or cycles,
etc., or such as being enabled for at least a portion of at least
one respiration phase or cycle once or more than once per hour,
day, week, etc. In other examples, the PA pressure sensor 105 can
be enabled during a respiration event, such as an apnea event, an
increased or decreased respiratory rate, etc.
[0118] In the example of FIG. 7, the processor 110 can be
configured to compute an indication of a reduction of blood supply
to at least a portion of the heart using information from the PA
pressure sensor 105, such as the PAP signal, and information from
the respiration phase detector 130, such as at least a portion of
at least one phase of the respiration signal.
[0119] FIG. 8 illustrates generally an example 800 of a
relationship between LV end-diastolic pressure ("LVEDP") 805 and PA
end-diastolic pressure ("PAEDP") 810, including a regression line
815.
[0120] Regression analysis is generally used to determine the
relationship between two or more measurements. A regression line of
a set of data is typically the line of best fit, or the line that
comes closest to all data points in the set. Correlation is
generally the degree to which the two or more measurements are
similar or related. A higher value of correlation corresponds to a
higher degree of relation. Cleaner and more accurate signals
typically have a higher value of correlation.
[0121] The present inventors have recognized that PAEDP generally
correlates to LVEDP. In the example of FIG. 8, the regression line
815 is the line of best fit for the data of LVEDP 805 versus PAEDP
810. The correlation of the LVEDP versus PAEDP of example 800 is
0.76. Thus, PA pressure information can be used to detect a
reduction of blood supply to at least a portion of the heart or an
occlusion of blood supply to at least a portion the heart, such as
ischemia, myocardial infarction, or other reduction or occlusion of
blood supply to at least a portion of the heart.
[0122] FIG. 9 illustrates generally an example 900 of LVEDP 905
during a balloon inflation 915 and a balloon deflation 920 and the
rate of pressure change in the LV ("LV dP/dt") 910 during the
balloon inflation 915 and the balloon deflation 920. Typically,
balloon inflation 915 and balloon deflation 920 in a blood vessel,
such as an artery or a vein, can be used to simulate a reduction of
blood supply to a portion of the body. In the example 900, the
reduction of blood supply is being simulated to the heart.
[0123] Generally, when the myocardium of the LV becomes acutely
ischemic, the LVEDP 905 and the LV volume increase. In FIG. 9,
during balloon inflation 915, LVEDP 905 increases roughly 10 mmHg.
During this same period, LV dP/dt 910 decreases roughly 500 mmHg/s.
Typically, as bodily activity increases, LVEDP increases. However,
as bodily activity increases, LV dP/dt generally increases as well.
Thus, by detecting LV dP/dt, it is possible to distinguish between
a reduction of blood supply to at least a portion of the heart and
an increase in LVEDP caused by activity.
[0124] FIG. 10 illustrates generally an example of a method 1000
including sensing a pulmonary artery pressure ("PAP") signal 1005
and computing an indication of a reduction of blood supply to at
least a portion of a heart 1010.
[0125] At 1005, a PAP signal is sensed. The PAP signal can include
any signal indicative of at least a portion of a PAP of a PA of a
subject, such as a PAD, a PAS, a mean PAP, a PAEDP, a PA dP/dt,
etc. In an example, the PAP signal can include a signal correlative
to at least a portion of a LV pressure signal of the subject, such
as a LV pressure, a LV diastolic pressure, a LV systolic pressure,
a LVEDP, a mean LV pressure, a LV volume, a LV dP/dt, etc. In an
example, the PAP signal can be sensed using the PA pressure sensor
105.
[0126] At 1010, a reduction of blood supply to at least a portion
of the heart is computed. In an example, the reduction of blood
supply to at least a portion of the heart can be computed using PAP
information, such as at least a portion of the PAP signal, at least
one PA pressure characteristic, at least one detected feature of
the at least one PA pressure characteristic, etc. In certain
examples, the reduction of blood supply to at least a portion of
the heart can be computed using a detected change in PAD, such as
an increase in PAD over a certain amount of time, a detected change
in PA dP/dt, such as a decrease in PA dP/dt over a certain amount
of time, or various combinations or permutations of detected
changes in PAP information over certain amounts of time, such as
synchronous or sequential intervals.
[0127] In an example, the reduction of blood supply to at least a
portion of the heart can be computed by comparing at least a
portion of the PAP information, such as the PAP, the PAD, the PAS,
the mean PAP, the PA dP/dt, etc., to a baseline, such as a
population-based baseline, a subject-based baseline, an absolute
baseline, and an adaptive baseline. In an example, the
population-based baseline can include a condition-specific
population-based baseline, such as a population-based baseline for
subjects having hypotension, hypertension, heart failure, other
conditions, or one or more than one combination or permutation of
one or more than one condition. In certain examples, the baseline
can be established or reestablished using the processor 110 and at
least a portion of the PAP information. In another example, the
indication of a reduction of blood supply to at least a portion of
the heart can be computed using information from the difference
between at least a portion of the PAP information and the
baseline.
[0128] FIG. 11 illustrates generally an example of a method 1100
including sensing a PAP signal, detecting at least one feature of
the PAP signal, detecting at least one interval between the at
least one feature of the PAP signal occurring at a first time and
the at least one feature of the PAP signal occurring at a second
time, and computing an indication of a reduction of blood supply to
at least a portion of a heart using the at least one interval.
[0129] At 1105, a PAP signal is sensed. The PAP signal can include
any signal indicative of at least a portion of a PAP of a PA of a
subject. In an example, the PAP signal can be sensed using the PA
pressure sensor 105.
[0130] At 1106, at least one feature of the PAP signal is detected.
The at least one feature of the PAP signal can include at least one
of at least one detected amplitude, at least one detected
magnitude, at least one detected peak, at least one detected
valley, at least one detected value, at least one detected change,
at least one detected increase, at least one detected decrease, and
at least one detected rate of change in the at least one PA
pressure characteristic. In an example, the at least one feature of
the PAP signal can be detected using the processor 110.
[0131] At 1107, at least one interval between at least one feature
of the PAP signal occurring at a first time and at least one
feature of the PAP signal occurring at a second time is detected.
In an example, the at least one interval can be detected using the
processor 110 including a time interval detector.
[0132] At 1111, an indication of a reduction of blood supply to at
least a portion of a heart can be computed using the at least one
interval. In an example, a reduction of blood supply to at least a
portion of the heart can be computed if the interval between a
first feature of the PAP signal occurring at a first time, such as
a detected PAD magnitude of a first level, and a second feature of
the PAP signal occurring at a second time, such as a detected PAD
magnitude of a second level, where the second level exceeds the
first level by a certain amount, e.g., 50 mmHg, occurs within a
certain amount of time, such as several seconds, e.g., 45 seconds.
In another example, a 25% reduction of blood supply to at least a
portion of the heart can be computed if the interval between a
first feature of the PAP signal occurring at a first time, such as
a detected LV dP/dt magnitude of a first level, and a second
feature of the PAP signal occurring at a second time, such as a
detected PAD magnitude of a second level, where the second level
falls to a certain amount below the first level, e.g., 500
mmHg/sec, occurs within a certain amount of time, such as several
seconds, e.g., 45 seconds.
[0133] FIG. 12 illustrates generally an example of a method 1200
including sensing a PAP signal, detecting an indication of mitral
valve performance using the PAP signal, and computing an indication
of a reduction of blood supply to at least a portion of a heart
using the detected mitral valve performance.
[0134] At 1205, a PAP signal is sensed. The PAP signal can include
any signal indicative of at least a portion of a PAP of a PA of a
subject. In an example, the PAP signal can be sensed using the PA
pressure sensor 105.
[0135] At 1208, an indication of mitral valve performance is
detected using the PAP signal. Generally, mitral valve performance
can include any indicator of mitral valve function or dysfunction,
such as mitral regurgitation ("MR"), mitral valve dysfunction,
improper mitral valve seat or closure, an abnormal or backward
pressure characteristic in a PAP signal or a LV pressure signal,
etc. The indication of mitral valve performance can be detected
using the PAP information, such as the PAP signal, the signal
correlative to at least a portion of a LV pressure signal, etc. In
an example, the indication of mitral valve performance can be
detected using abnormal pressure variations in the PAP signal
indicative of an abnormal or backward pressure characteristic, or
other mitral valve indicator.
[0136] At 1212, an indication of a reduction of blood supply to at
least a portion of the heart is computed using the detected mitral
valve performance. Typically, an indicator of ischemia, myocardial
infarction, or other reduction in blood supply to the heart, can
include mitral valve performance, such as MR or other mitral valve
dysfunction. In an example, if the detected mitral valve
performance indicates mitral valve dysfunction, MR, improper mitral
valve seat or closure, an abnormal or backward pressure
characteristic, etc., then an indication of a reduction of blood
supply to at least a portion of the heart can be computed.
[0137] FIG. 13 illustrates generally an example of a method 1300
including sensing a PAP signal, sensing a different physiological
signal, and computing an indication of a reduction of blood supply
to at least a portion of a heart using the PAP signal and the
different physiological signal.
[0138] At 1305, a PAP signal is sensed. The PAP signal can include
any signal indicative of at least a portion of a PAP of a PA of a
subject. In an example, the PAP signal can be sensed using the PA
pressure sensor 105.
[0139] In an example, at 1305, the PAP signal is sensed
continuously. In another example, the sensing the PAP signal can be
triggered using information from the different physiological
signal, such as heart-rate variability ("HRV") information,
heart-rate ("HR") information, etc. In an example, if the HRV
information or HR information deviates from an established
baseline, the sensing the PAP signal can be triggered. Generally,
triggering the sensing the PAP signal can reduce power consumption
in the PA pressure sensor 105.
[0140] At 1309, a different physiological signal is sensed. The
different physiological signal can include a physiological signal
different than the PAP signal. In an example, the different
physiological signal can include a physiological signal indicative
of a reduction of blood supply to at least a portion of the heart,
such as a cardiac signal, a heart sound signal, a right ventricular
pressure signal, a left ventricular pressure signal, a blood
pressure signal, an oxygen saturation signal, etc. In certain
examples, the different physiological signal can be sensed using at
least one of the auxiliary physiological sensor 115, the cardiac
sensor 116, the heart sound sensor 117, the right ventricular
pressure sensor 118, the left ventricular pressure sensor 119, the
blood pressure sensor 120, the oxygen saturation sensor 121, or
other physiological sensor capable of sensing a signal indicative
of a reduction of blood supply to at least a portion of the
heart.
[0141] In an example, at 1309, the different physiological signal
can include at least a portion of the cardiac signal, such as the
ST-segment of an ECG signal. Generally, the ST-segment of the ECG
signal can be indicative of a reduction of blood supply to at least
a portion of the heart. In an example, the ST-segment of the ECG
signal can be detected using the cardiac sensor 116.
[0142] In another example, at 1309, the different physiological
signal can include an impedance signal, such as a cardiac impedance
signal. Generally, the cardiac impedance signal can be used to
estimate a ventricular blood volume of the heart, and the
ventricular blood volume of the heart can be indicative of a
reduction of blood supply to at least a portion of the heart. In an
example, the cardiac impedance signal can be detected using the
impedance sensor.
[0143] In another example, at 1309, the different physiological
signal can include an acceleration signal, such as a left
ventricular acceleration signal. Generally, the acceleration signal
can be indicative of a reduction of blood supply to at least a
portion of the heart. In an example, the left ventricular
acceleration signal can be detected using an accelerometer, such as
a lead based accelerometer.
[0144] In other examples, the different physiological signal can
include a physiological signal that is not indicative of a
reduction of blood supply to at least a portion of the heart, such
as an activity signal, a posture signal, or a respiration signal.
In certain examples, the different physiological signals can be
used to increase the sensitivity, sensitivity, or other function of
one or more than one sensor, such as the PA pressure sensor 105. In
certain examples, the different physiological signal that is not
indicative of a reduction of blood supply to at least a portion of
the heart can be detected using an activity sensor, a posture
sensor, a respiration sensor, or other different physiological
sensor.
[0145] At 1313, an indication of a reduction of blood supply to at
least a portion of the heart can be computed using the PAP signal
and the different physiological signal. Typically, using multiple
sensors to sense the same or similar condition can increase the
sensitivity or specificity of the sensing. In an example, the
indication of a reduction of blood supply to at least a portion of
the heart can be computed using the processor 110.
[0146] In an example, at 1313, an indication of a reduction of
blood supply to at least a portion of the heart can be computed
using the PAP signal and the cardiac signal, such as the ST-segment
of the ECG signal. Typically, an elevated ST-segment, or an
ST-segment that deviates from an established baseline, can be
indicative of various physiological conditions ranging from an
elevated heart rate, a change in position of the subject, ischemia,
myocardial infarction, etc. Thus, by detecting an elevation in the
ST-segment or a deviation from an established baseline ST-segment
as well as using the PAP signal, an indication of a reduction in
blood supply to at least a portion of the heart can be computed
with an increased sensitivity or specificity.
[0147] In an example, at 1313, the indication of a reduction of
blood supply to at least a portion of the heart can be computed
using the PAP signal and the activity signal. Generally, the
likelihood of ischemia, or other reduction of blood supply to at
least a portion of the heart, is greater when the patient is
active. In an example, the threshold, the baseline, etc., can be
adapted to account for an increase in activity when computing the
indication of a reduction of blood supply to at least a portion of
the heart.
[0148] In an example, at 1313, the indication of a reduction of
blood supply to at least a portion of the heart can be computed
using the PAP signal, the different physiological signal, and at
least one weighting factor for the PAP signal or the different
physiological signal. Generally, different sensors have different
detection sensitivity of specificity. Thus, an indication computed
using a first signal may be a more accurate indication of a
reduction of blood supply to at least a portion of the heart than
by using a second signal. In certain examples, the at least one
weighting factor can include at least one of a signal-to-noise
ratio ("SNR") and a performance metric, where a performance metric
can include at least one of a signal sensitivity, a signal
specificity, a positive prediction value ("PPV"), a negative
prediction value ("NPV"), or other performance metrics.
[0149] In another example, at 1313, the indication of a reduction
of blood supply to at least a portion of the heart can be computed
using a temporal profile. In an example, the temporal profile can
include using the PAP signal and the different physiological signal
in a sequential manner, such as by detecting a first indication in
a first signal, such as the PAP signal, and then detecting a second
indication in a second signal, such as the different physiological
signal.
[0150] In another example, at 1313, the indication of a reduction
of blood supply to at least a portion of the heart can be computed
by merging decisions from different sensors, such as by using fuzzy
logic or other mathematical algorithm or operation.
[0151] FIG. 14 illustrates generally an example of a method 1400
including sensing a PAP signal, detecting at least one feature of
the PAP signal, sensing a different physiological signal, detecting
at least one feature of the different physiological signal,
detecting at least one interval between the at least one different
physiological signal feature and the at least one PAP signal
feature, and computing an indication of a reduction of blood supply
to at least a portion of a heart using the at least one
interval.
[0152] At 1405, a PAP signal is sensed. The PAP signal can include
any signal indicative of at least a portion of a PAP of a PA of a
subject. In an example, the PAP signal can be sensed using the PA
pressure sensor 105.
[0153] At 1406, at least one feature of the PAP signal is detected.
Generally, the at least one feature of the PAP signal can include
any distinguishable feature of the PAP signal. The at least one
feature of the PAP signal can include at least one of at least one
detected amplitude, at least one detected magnitude, at least one
detected peak, at least one detected valley, at least one detected
value, at least one detected change, at least one detected
increase, at least one detected decrease, and at least one detected
rate of change in the PAP signal, such as the PAD, the PA dP/dt,
the signal correlative to the LVEDP, etc.
[0154] At 1415, a different physiological signal is sensed. In
certain examples, the different physiological signal can include at
least one of a cardiac signal, a heart sound signal, a right
ventricular pressure signal, a left ventricular pressure signal, a
blood pressure signal, an oxygen saturation signal, or other
physiological signal indicative of a reduction of blood supply to
at least a portion of the heart.
[0155] In an example, at 1415, the different physiological signal
includes the cardiac signal. The cardiac signal can include any
signal indicative of the electrical or mechanical cardiac activity
of a heart. In an example, the cardiac signal can be sensed using
the cardiac sensor 116.
[0156] At 1416, at least one feature of the different physiological
signal is detected. Generally, the at least one feature of the
different physiological signal can include any distinguishable
feature of the different physiological signal.
[0157] In an example, at 1416, the at least one feature of the
different physiological signal includes at least one feature of the
cardiac signal. The at least one feature of the cardiac signal can
include at least one feature or component of an ECG signal, e.g.,
at least one component of a P-wave, at least one component of a
Q-wave, at least one component of a R-wave, at least one component
of a S-wave, at least one component of a T-wave, or any combination
or permutation of features or components of the ECG signal, or any
mechanical cardiac features of a pressure signal or acceleration
signal indicative of the cardiac activity of a subject.
[0158] At 1420, at least one interval between the at least one
different physiological signal feature and the at least one PAP
signal feature is detected. In an example, the at least one
interval can be detected using the processor 110.
[0159] At 1425, an indication of a reduction of blood supply to at
least a portion of the heart is computed using the at least one
interval between the at least one different physiological signal
feature and the at least one PAP signal feature. Typically, the
interval between physiological signal features can be indicative of
a physiological event, e.g., the PAP of a subject generally rises
slower during ischemia, increasing the interval between certain
physiological markers and PAP signal features. In an example, an
increasing interval between a cardiac signal feature, such as at
least one component of the Q-wave or R-wave, and a PAP signal
feature, such as at least one component of the PAD pressure, PAS
pressure, etc., can be indicative of a reduction of blood supply to
at least a portion of the heart.
[0160] FIG. 15 illustrates generally an example of a method 1500
including sensing a PAP signal, sensing a respiration signal,
detecting at least a portion of at least one phase of the
respiration signal, forming a composite signal using at least a
portion of the PAP signal over at least a portion of at least one
phase of the respiration signal, obtaining a gated PAP signal using
information from the respiration signal, enabling or disabling the
sensing the PAP signal using at least a portion of at least one
phase of the respiration signal, and computing an indication of a
reduction of blood supply to at least a portion of a heart.
[0161] At 1505, a PAP signal is sensed. The PAP signal can include
any signal indicative of at least a portion of a PAP of a PA of a
subject. In an example, the PAP signal can be sensed using the PA
pressure sensor 105.
[0162] At 1530, a respiration signal is sensed. The respiration
signal can include any signal indicative of the respiration of a
subject, such as inspiration, expiration, or any combination,
permutation, or component of the respiration of the subject. In an
example, the respiration signal can be sensed using the respiration
sensor 125.
[0163] At 1535, at least a portion of at least one phase of the
respiration signal is detected. The at least one phase of the
respiration signal can be detected using the respiration signal. In
certain examples, the at least one phase of the respiration signal
includes at least a portion of at least one of an inspiration, an
expiration, a transition between inspiration and expiration, a
transition between expiration and inspiration, etc. In certain
examples, an inspiration, an expiration, the transitions between
inspiration and expiration, etc., can be determined using the
respiration signal, such as by differentiating the respiration
signal to attain the slope of the respiration signal, by detecting
peaks and valleys of the respiration signal, or by using other
filtering methods or signal characteristics. In an example, the at
least one phase of the respiration signal can be detected using the
respiration phase detector 130.
[0164] In an example, at 1535, the at least one phase of the
respiration signal includes an inspiration of one respiration
cycle. A respiration cycle can include one full inspiration and
expiration, one full expiration and inspiration, or any permutation
or combination of a full inspiration and a full expiration. In
other examples, the at least one phase of the respiration signal
includes an expiration of one respiration cycle, a portion of an
inspiration of one respiration cycle, a portion of an expiration of
one respiration cycle, a portion of an inspiration and an
expiration of one respiration cycle, a portion of an inspiration or
an expiration of more than one respiration cycle, a portion of an
inspiration and an expiration of more than one respiration cycle,
etc.
[0165] At 1536, a composite signal is formed using at least a
portion of the PAP signal over at least a portion of at least one
phase of the respiration signal. Generally, forming a composite
physiological signal over at least a portion of at least one phase
of the respiration signal can remove noise or variation from the
physiological signal due to respiration. In an example, the
composite signal can include an average signal. In certain
examples, the average signal can include an average PAS pressure
signal over at least a portion of at least one phase of the
respiration signal, such as inspiration, expiration, etc., an
average PAD pressure signal over at least a portion of at least one
phase of the respiration signal, etc.
[0166] At 1537, a gated PAP signal is obtained using information
from the respiration signal. Typically, the PAP signal can be gated
in order to detect at least a portion of the PAP signal, such as
PAS during inspiration or expiration, PAD during inspiration or
expiration, etc. In an example, the PAP signal can be gated using
the processor 110.
[0167] In an example, at 1537, the PAP signal, or at least one
characteristic or feature of-the PAP signal, can be gated during at
least a portion of a first phase of the respiration signal, such as
during at least a portion of inspiration, or at least a portion of
expiration. In another example, the PAP signal, or at least one
characteristic or feature of the PAP signal, can be gated using at
least one feature of the respiration signal, such as the transition
from inspiration to expiration, the transition from expiration to
inspiration, etc., and a time interval, such as a time interval of
100-300 milliseconds, etc.
[0168] In other examples, a gated PAP signal can be obtained using
information from the cardiac signal, such as the at least one
feature or component of an ECG signal, or using information from
the activity signal, such as when the subject is inactive.
[0169] At 1538, the sensing the PAP signal is enabled or disabled
using at least a portion of at least one phase of the respiration
signal. In an example, the PAP signal is sensed using the PA
pressure sensor 105. Generally, enabling or disabling the PA
pressure sensor can reduce power consumption. The sensing the PAP
signal can be enabled or disabled during at least a portion of at
least one phase of the respiration signal during at least one
specific respiration cycle or time period, such as during
inspiration every fifth respiration cycle, or during inspiration
for ten consecutive respiration cycles once per hour, etc. In other
examples, the sensing the PAP signal can be enabled during specific
respiratory events, such as an apnea event, an increased or
decreased respiratory rate, etc., or disabled during specific
respiratory events, such as during normal respiratory function.
[0170] In other examples, the sensing the PAP signal can be enabled
or disabled using information from the cardiac signal, such as
enabling or disabling the sensing the PAP signal using the at least
one feature of component of an ECG signal, or using information
from the activity signal, such as enabling or disabling the sensing
the PAP signal when the subject is inactive.
[0171] At 1540, an indication of a reduction of blood supply to at
least a portion of the heart is computed using at least one of the
composite signal, the gated PAP signal, and the enabled or disabled
PAP signal. In an example, at 1540, the composite signal can be
compared to a baseline, such as a baseline composite signal
established using the processor 110 and the composite signal. In an
example, if the composite signal deviates from the baseline, an
indication of a reduction of blood supply to at least a portion of
the heart can be computed. In another example, at 1540, the gated
PAP signal can be compared to a baseline, such as a baseline gated
PAP signal established or reestablished using the processor 1 10
and the gated PAP signal. In an example, if the gated PAP signal
deviates from the baseline, an indication of a reduction of blood
supply to at least a portion of the heart can be computed. In
another example, at 1540, the enabled or disabled PAP signal can be
compared to a baseline, such as a baseline enabled or disabled PAP
signal established or reestablished using the processor 110 and the
enabled or disabled PAP signal. In an example, if the enabled or
disabled PAP signal deviates from the baseline, an indication of a
reduction of blood supply to at least a portion of the heart can be
computed.
[0172] In other examples, at 1540, other methods can be used to
compute an indication of a reduction of blood supply to at least a
portion of the heart using at least one of the composite signal,
the gated PAP signal, and the enabled or disabled PAP signal, such
as those disclosed in methods 1000-1400.
[0173] FIGS. 1-15 illustrate various examples, including sensing a
pulmonary artery pressure ("PAP") signal, detecting at least one
feature of the PAP signal, detecting at least one interval between
the at least one feature of the PAP signal occurring at a first
time and the at least one feature of the PAP signal occurring at a
second time, detecting an indication of mitral valve performance
using the PAP signal, sensing a different physiological signal,
sensing a cardiac signal, detecting at least one feature of the
cardiac signal, detecting at least one interval between the at
least one cardiac signal feature and the at least one PAP signal
feature, sensing a respiration signal, detecting at least a portion
of at least one phase of the respiration signal, forming a
composite signal using at least a portion of the PAP signal over at
least a portion of at least one phase of the respiration signal,
obtaining a gated PAP signal using information from the respiration
signal, enabling or disabling the sensing the PAP signal using at
least a portion of at least one phase of the respiration signal,
and computing an indication of a reduction of blood supply to at
least a portion of a heart, etc., are disclosed. It is to be
understood that these examples are not exclusive, and can be
implemented either alone or in combination, or in various
permutations or combinations.
[0174] It is to be understood that the above description is
intended to be illustrative, and not restrictive. For example, the
above-described embodiments (and/or aspects thereof) may be used in
combination with each other. Many other embodiments will be
apparent to those of skill in the art upon reviewing the above
description. The scope of the invention should, therefore, be
determined with reference to the appended claims, along with the
full scope of equivalents to which such claims are entitled. In the
appended claims, the terms "including" and "in which" are used as
the plain-English equivalents of the respective terms "comprising"
and "wherein." Also, in the following claims, the terms "including"
and "comprising" are open-ended, that is, a system, device,
article, or process that includes elements in addition to those
listed after such a term in a claim are still deemed to fall within
the scope of that claim. Moreover, in the following claims, the
terms "first," "second," and "third," etc. are used merely as
labels, and are not intended to impose numerical requirements on
their objects.
[0175] The Abstract is provided to comply with 37 C.F.R.
.sctn.1.72(b), which requires that it allow the reader to quickly
ascertain the nature of the technical disclosure. It is submitted
with the understanding that it will not be used to interpret or
limit the scope or meaning of the claims. Also, in the above
Detailed Description, various features may be grouped together to
streamline the disclosure. This should not be interpreted as
intending that an unclaimed disclosed feature is essential to any
claim. Rather, inventive subject matter may lie in less than all
features of a particular disclosed embodiment. Thus, the following
claims are hereby incorporated into the Detailed Description, with
each claim standing on its own as a separate embodiment.
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